hiv, leptospirosis hepatitis b

Human immunodeficiency virus (HIV)

Human Immunodeficiency Virus (HIV)

CHARACTERISTICS• Single stranded RNA• reverse transcriptase• Envelope of phospholipid (has glycoprotein

spikes termed gp120• Belongs to Type D Retrovirus

TRANSMISSIONRoute of HIV Transmission include:• Intimate sexual contact- most dangerous is the “anal

receptive intercourse”• Breast milk• Transplacental infection of a fetus• Blood-contained needles• Organ transplants• Artificial insemination• Blood transfusion

Human Immunodeficiency virus (HIV)

TRANSMISSION• Requires transfer/ direct contact with infected

body fluids• Blood- contains 1000 to 100,000 infective viruses

per milliliter• Semen- contains 10 to 50 viruses per milliliter

INCUBATION PERIOD• Average of 8 years

Human Immunodeficiency Virus (HIV)

DISEASE• Acquired Immunodeficiency Syndrome (AIDS)

– condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections.

– HIV causes AIDS by damaging the immune system cells until the immune system can no longer fight off other infections that it would usually be able to prevent.


STAGES OF HIV INFECTION:1. Category A- asymptomatic; may cause

swollen lymph nodes2. Category B- infections by the yeast Candida

Albicans, which can appear in the mouth, throat, or vagina; whitish patches on the oral mucosa

3. Category C- This stage is clinical AIDS


TREATMENT• Azidothymidine, Didanosine (ddl), Zalcitabine (ddc)

to inhibit viral replication• Current treatment for HIV infection consists of highly

active antiretroviral therapy, or HAART.• Treatment of opportunistic infections depends on the

organisms


PREVENTION• AWARENESS!• All adolescents should have access to HIV screening• Abstaining from sex or using safe-sex practices.

• HIV-infected women should avoid pregnancy. • If an infected woman becomes pregnant, anti-HIV drugs are

fairly effective at minimizing transmission. • Also, caesarean delivery reduces the baby's risk of acquiring

HIV infection.• HIV-infected mothers should bottle-feed their babies


Hepatitis B Virus

CHARACTERISTICS OF THE VIRUS• Incomplete circular double stranded DNA with

lipid envelope and DNA polymerase; I Type• one of the smallest enveloped animal viruses,

with a virion diameter of 42 nm• consists of a core particle which is made up of

DNA and the core antigen (HBcAg).• The envelope contains the surface antigen

(HBsAg).

Hepatitis B Virus

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Hepatitis B Virus

TRANSMISSION• Exposure to infectious blood or body fluids containing

blood. • Possible forms include sexual contact, blood transfusions,

re-use of contaminated needles & syringes, and vertical transmission from mother to child during childbirth.

INCUBATION PERIOD• The incubation period before the appearance of

symptoms averages about 12 weeks• The range is about 4-26 weeks

DISEASE• Viral Hepatitis B or Serum Hepatitis

– Infection of liver and blood characterized by weakness, nausea, joint pain, abdominal discomfort fever and jaundice that is likely to progress to severe liver damage

Hepatitis B Virus

PATHOGENESIS• The hepatitis B virus primarily interferes with the

functions of the liver by replicating in liver cell• During HBV infection, the host immune response causes

both hepatocellular damage and viral clearance.• antigen nonspecific inflammatory cells can worsen the

cytotoxic T Lymphocyte-induced immunopathology• platelet activated at the site of infection facilitate the

accumulation of CTLs into the liver.

Hepatitis B Virus

RELEVANCE TO DENTISTRY• Instances of transmission to patients by

dentists and surgeons• Failure to sterilize needles (intravenous drugs)• Dentists who are in daily contact with blood

have a considerably higher incidence of HBV than members of general population.

Hepatitis B Virus

TREATMENT• It does not usually require treatment because

most adults clear the infection spontaneously. • Drugs can stop the virus from replicating, and

prevent liver damage such as cirrhosis and liver cancer.

• Treatments include antiviral drugs such as lamivudine, adefovir and entecavir, and immune system modulators such as interferon alpha.

Hepatitis B Virus

PREVENTIONAvoid:• unprotected sexual contact• blood transfusions• re-use of contaminated needles and syringes,• transmission during child birth• Infants may be vaccinated at birth

Hepatitis B Virus

PREVENTION• Hepatitis B surface antigen vaccine confers

active immunity• Hepatitis B immunoglobulin confers passive

immunity

Hepatitis B Virus

Hepatitis B Virus

Leptospira Interrogans

CHARACTERISTICS• Obligate aerobe spirochete• Gram-negative-like cell envelope consisting of a

cytoplasmic and outer membrane. • 2 flagella of Leptospira extend from the

cytoplasmic membrane into the periplasmic space; necessary for the motility of Leptospira.

• Slow growing in culture• Survives in a moist environment for weeks-months


HABITAT & TRANSMISSION• Wild and domestic animals• Direct contact of the skin, esp. open wounds

with water, moist soil or vegetation contaminated with rat urine


DISEASE• Leptospirosis- infection of organs, including

liver and kidney, due to immunopathologic reaction against pathogen characterized by:– Flu-like symptoms– Jaundice– Organ damage


PATHOGENESIS• No toxins or virulence known• Occurs as an initial bacterimic phase• subsequent immunopathologic consequences

in kidney and liverINCUBATION PERIOD• 7-19 days, with average of 10 days.


TREATMENT• treatment of leptospirosis involves high doses

of antibiotics: Penicillin G or Tetracycline

PREVENTION• Rat control• Vaccination of domestic pets• Doxycycline for short-term exposure


petechial rash conjunctival suffusion

hiv, leptospirosis hepatitis b

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